Patent Literature 1 and Patent Literature 2 disclose two-motor vehicle-driving apparatuses, each composed of: two electric motors each for driving one of a left and a right driving wheels independently from each other; and speed reducers.
A two-motor vehicle-driving apparatus of this kind provides an advantage that unlike a one-motor vehicle-driving apparatus in which a single motor must drive both the left and the right driving wheels, it does not require differential gears and other components for dividing the driving power from a single electric motor to left and right.
Also, since the two-motor vehicle driving apparatus has an electric motor for individually driving the left and the right driving wheels independently from each other, it is easy to drive the left and the right driving wheels with different amounts of power from each other, and therefore it is easy to improve traveling performance through improved turning capability for example, by supplying a greater amount of driving power to a radially outer driving wheel than to a radially inner driving wheel during a turn.
As shown in FIG. 6 or FIG. 7, a two-motor vehicle driving apparatus includes: a left and a right electric motors 101 for driving the left and right driving wheels independently from each other; and two speed reducers 102 for reducing rotation speed of the electric motors 101; the two speed reducers 102 are disposed in the middle between the left and right electric motors 101.
As shown in FIG. 6 or FIG. 7, each speed reducer 102 is provided by a parallel-gear speed reducer which includes: an input gear shaft 123 having an input gear 123a for receiving driving power from a motor shaft 112; an intermediate gear shaft 124 having a large-diameter gear 124a for engagement with the input gear 123a of the gear shaft 123, and a small-diameter gear 124b for engagement with an output gear 125a; and an output gear shaft 125 having the output gear, extended from a speed reducer casing 128 for transmitting the driving power to the driving wheel via a constant velocity joint 126 and an intermediate shaft 127.